Multijoule, output energy excimer avalanche discharge lasers which are also capable of high average power operation are potentially useful in applications such as laser marking of metals, laser processing of semiconductor materials and large scale UV photolithography. Considerable success has been obtained in scaling the output energy of excimer lasers using low impedance pulse forming lines (PFL's) charged to high voltages together with low inductance transfer switches to isolate the PFL from the laser head. Closure of the transfer switch generates a very fast risetime voltage pulse across the laser electrodes resulting in a gas breakdown voltage well in excess (typically.times.5) of the steady-state discharge voltage (V.sub.s). These highly overvolted discharges are both volume scalable and stable for relatively long periods of time (100-200 ns). See IEEE Journal of Quantum Electronics, Vol. QE-19, p. 416 (1983) by R. S. Taylor et al and Appl. Phys. Lett. Vol 39, p. 297 (1981) by J. L. Levatter et al. A magnetic switch can also be used as a transfer gap as taught in U.S. Pat. No. 4,275,317, June 23, 1981 (Frosch et al). In the early 1970's auxiliary spiker or pulser circuits were used to sustain low pressure CO.sub.2 laser discharges. See J. Appl. Phys. Vol. 43, NO. 8 August 1972 p. 3411 et seq. by J. P. Reilly. Recently a similar circuit was used in conjunction with the PFL-rail-gap switch excitation scheme to generate a high voltage pulse across a pair of XeCl laser electrodes to initiate gas breakdown. See Appl. Phys. Lett. Vol. 43 p. 735 (1983) by W. H. Long, Jr. et al. Since the voltage on the PFL was not required to break down the gas, the PFL could be charged to 2 V.sub.s in order to satisfy the impedance matching conditions for a constant voltage laser load. The improved energy transfer efficiency from the PFL to the XeCl discharge made possible by impedance matching resulting in a .about.3% overall (including the pulse circuit) electrical to optical efficiency. However with this and other scaling approaches involving transfer gaps, the switch must transfer the entire energy stored on the PFL. For single-shot applications, this does not pose a serious problem; however, for high average power applications, concerns about switch reliability and lifetime can best be addressed if the voltage and the energy transferred by the switch are reduced.